Dynamic Stiffness Identification of Bolted Joints

2011 ◽  
Vol 291-294 ◽  
pp. 1582-1588
Author(s):  
Tie Neng Guo ◽  
Bin Song ◽  
Dong Liang Guo ◽  
Zhong Qing Chen
Keyword(s):  
Dynamic Characteristic ◽  
Dynamic Stiffness ◽  
Dynamic Parameter ◽  
High Accuracy ◽  
Bolted Joints ◽  
Small Discrepancy ◽  
Identification Method ◽  
Stiffness Identification ◽  
Accuracy Result ◽  
The Relationship

The joint has a significant effect on the dynamic characteristic of the mechanism, and the identification of the stiffness of the joints has become a key problem. In this paper, a method is presented for identifying the dynamic characteristic of joints. An experiment is designed to test the dynamic parameter of the bolted joints specimen; the identification method, based on experiment, has a high accuracy result. By taking a specimen to experiment and identify the dynamic characteristic of joints, the relationship between the preload on the bolts and the joints stiffness is acquired. In order to validate the accuracy of the result, the FEM software is used to simulate. There are only a small discrepancy between the results of identification and simulation.

scholarly journals An improved parameter identification method of redundant manipulator

2021 ◽  
Vol 18 (2) ◽  
pp. 172988142110021
Author(s):  
Shi-Ping Liu ◽  
Zi-Yan Ma ◽  
Jin-Liang Chen ◽  
Jun-Feng Cao ◽  
Yan Fu ◽  
...  
Keyword(s):  
Parameter Identification ◽  
Viscous Friction ◽  
Dynamic Parameter ◽  
High Accuracy ◽  
Friction Model ◽  
Service Robot ◽  
Redundant Manipulator ◽  
Spinor Theory ◽  
Identification Method ◽  
Optimization Function

To achieve more accurate simulation and control in the use of the manipulator, it is necessary to establish an accurate dynamic model of the redundant manipulator. The research of this article focuses on the dynamic parameter identification method of the redundant manipulator. In the study, the spinor theory is applied to the Newton–Euler dynamic equation, the Coulomb + viscous friction model is adopted, and the minimum parameter set is obtained by linearization derivation. The parameter identification of the manipulator is realized using the method of offline identification of the measured current, and the coefficient of the excitation trajectory is optimized using the nonlinear optimization function. Finally, the parameter set with high accuracy is obtained, and the motion trajectory of each joint can be obtained. The scheme has high accuracy and can meet the needs of practical application. To verify the accuracy and reliability of this method, we have carried out experiments on a service robot “Walker” and obtained the desired results.

Dynamic Characteristic of HSK Tooling System

2006 ◽  
Vol 315-316 ◽  
pp. 440-444
Author(s):  
Gui Cheng Wang ◽  
S.L. Wang ◽  
Hong Jie Pei ◽  
Wei Guo Wu ◽  
X.J. Hua
Keyword(s):  
Dynamic Characteristic ◽  
Rotational Speed ◽  
High Speed ◽  
Dynamic Stiffness ◽  
Loading Capacity ◽  
High Speed Machining ◽  
Depth Analysis ◽  
Tooling System ◽  
The Relationship ◽  
High Speed Machine

According to in-depth analysis of the interface between HSK shank and the spindle, the dynamic characteristic of HSK tool system in high speed machining is studied and numerical simulation is carried out with FEM. The HSK tool system deformation, contact stress and the change law of dynamic stiffness were opened out systematically. The relationship between the dynamic stiffness and loading capacity was given. The rotational speed per minute when HSK taper coordination position fails can be named limit maximum rotational speed Nmax of HSK. This provides the foundation for the design of the high speed machine tool.

Analysis of magnetic force and dynamic characteristic for non-contact permanent magnet linear drive device

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1337-1345
Author(s):  
Chuan Zhao ◽  
Feng Sun ◽  
Junjie Jin ◽  
Mingwei Bo ◽  
Fangchao Xu ◽  
...  
Keyword(s):  
Finite Element ◽  
Permanent Magnet ◽  
Dynamic Characteristic ◽  
Driving Force ◽  
Magnetic Circuit ◽  
Response Speed ◽  
Computation Method ◽  
Element Analysis ◽  
Element Simulation ◽  
The Relationship

This paper proposes a computation method using the equivalent magnetic circuit to analyze the driving force for the non-contact permanent magnet linear drive system. In this device, the magnetic driving force is related to the rotation angle of driving wheels. The relationship is verified by finite element analysis and measuring experiments. The result of finite element simulation is in good agreement with the model established by the equivalent magnetic circuit. Then experiments of displacement control are carried out to test the dynamic characteristic of this system. The controller of the system adopts the combination control of displacement and angle. The results indicate that the system has good performance in steady-state error and response speed, while the maximum overshoot needs to be reduced.

Effects of countersunk hole geometry errors on the fatigue performance of CFRP bolted joints

2021 ◽  
pp. 095440542110285
Author(s):  
Xuda Qin ◽  
Xingfeng Cao ◽  
Hao Li ◽  
Meng Zhou ◽  
Ende Ge ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Bolted Joints ◽  
Fatigue Performance ◽  
Machining Process ◽  
Fe Model ◽  
Hole Making ◽  
Hole Geometry ◽  
Geometry Error ◽  
The Relationship ◽  
Hole Machining

Due to good aerodynamic performance and reliability, countersunk bolt joint is one of the most commonly used connection methods for carbon fiber reinforced polymer (CFRP) components in the aircraft. However, the countersunk hole machining process is inevitably accompanied by geometric errors, which will directly affect the mechanical properties of the joint structure. This paper presents a numerical and experimental investigation on the effect of countersunk hole geometry errors on the fatigue performance of CFRP bolted joints. FE model of CFRP countersunk bolted joints with designed geometry errors are established, and the rationality of the FE analysis was verified by fatigue life and failure forms. The CFRP bolted structure failure mechanism under fatigue load and influence of hole-making geometry error (including countersunk fillets radius, countersunk depth, and countersunk angle) on the fatigue life are investigated. Based on the relationship between fatigue life and the geometry error, the corresponding tolerances for CFRP bolt joint countersunk hole are determined as well. The research results can provide a reference for establishing reasonable geometric accuracy requirements for CFRP joint hole machining.

ANALYSIS OF THE ERROR IN DETERMINING THE EQUIVALENT SIZE OF A DEFECT BY THE STANDARDLESS METHOD DURING ULTRASONIC TESTING

2021 ◽  
pp. 50-57
Author(s):  
A. N. Kireev ◽  
M. A. Kireeva
Keyword(s):  
Relative Error ◽  
High Reliability ◽  
Ultrasonic Method ◽  
Experimental Studies ◽  
Standard Samples ◽  
Defect Identification ◽  
Identification Method ◽  
Maximum Value ◽  
Software Product ◽  
The Relationship

The article provides a review and analysis of the defect identification method for determining the size of discontinuities when diagnosing various machine parts and units by the manual ultrasonic method. This method makes it possible to determine the equivalent size of discontinuities of various types without using standard samples of an enterprise: point planar and volumetric; extended planar and volumetric. The method is based on the use of the relationship between the amplitude and time characteristics of the echo signal from the discontinuity and the backside signal in the object being diagnosed and the equivalent size of the discontinuity. The article presents the mathematical apparatus for the implementation of this method. Also presented is a software product that allows you to automate calculations when using this defect identification method. The article contains experimental studies of the method for determining the equivalent dimensions of discontinuities of various types, which have shown its high reliability. The maximum value of the relative error in determining the equivalent size of a point planar discontinuity was 2.867 %. The maximum value of the relative error in determining the equivalent size of a point volumetric discontinuity was 1.986 %. The maximum value of the relative error in determining the transverse equivalent size of an extended planar discontinuity was 0.667 %. The maximum value of the relative error in determining the transverse equivalent size of an extended volumetric discontinuity was 1.95 %.

An Experimental Study of Self-Loosening of Bolted Joints

2004 ◽  
Vol 126 (5) ◽  
pp. 925-931 ◽  
Author(s):  
Yanyao Jiang ◽  
Ming Zhang ◽  
Tae-Won Park ◽  
Chu-Hwa Lee
Keyword(s):  
Endurance Limit ◽  
Early Stage ◽  
Fatigue Curve ◽  
Relative Displacement ◽  
Shear Loading ◽  
Bolted Joints ◽  
Second Stage ◽  
Controlling Parameter ◽  
Cyclic Plastic Deformation ◽  
The Relationship

The self-loosening process of a bolted joint consists of two distinct stages. The early stage of self-loosening is due to the cyclic plastic deformation of the materials. The second stage of self-loosening is characterized by the backing off of the nut. The current work is concentrated on an experimental investigation of the second stage self-loosening. Over one hundred bolted joints with M12×1.75 bolts and nuts were experimentally tested using a specially designed testing apparatus. The experiments mimicked two plates jointed by a bolt and a nut and were subjected to cyclic transverse shear loading. During an experiment, the relative displacement between the two clamped plates, denoted by δ, was a controlling parameter. For a given preload, the relationship between, Δδ/2, the amplitude of the relative displacement between the two clamped plates, and, NL, the number of loading cycles to loosening followed a pattern similar to a fatigue curve. There existed an endurance limit below which self-loosening would not persist. A larger preload resulted in a larger endurance limit. However, a large preload increased the possibility for the bolt to fail in fatigue. The results suggest that the use of a regular nut is superior to the use of a flange nut in terms of self-loosening resistance.

Non-Linear Analysis and Modeling of the Structure with Bolted Joints

2015 ◽  
Vol 656-657 ◽  
pp. 694-699
Author(s):  
Xin Liao ◽  
Jian Run Zhang ◽  
Dong Lu
Keyword(s):  
Dynamic Stiffness ◽  
Element Model ◽  
Outer Radius ◽  
Bolted Joints ◽  
Structure Model ◽  
Test Results ◽  
Bolted Joint ◽  
Joint Structure ◽  
Non Linear ◽  
Simulation Results

In this study, a non-linear finite element model for a simplified single-bolted joint structure model is built. Static analysis on the structure under different shear force and pretension effect is done, and the non-linear contact behavior is analyzed. Through comparing datum, it is found that interface area of each bolted joint region can be described an annular region around bolt hole, whose outer radius has increased by 85% compared with radius of bolt hole. Also, the frequency responses of the multi-bolted joint structure under sinusoidal excitation are investigated. Simulation results show that the resonance regions basically remain unchanged in different pretension effect and the largest amplitude will increase with the increasing preloads. Finally, the vibration experiments are conducted. Interface nonlinear affect dynamic stiffness considerably. The test results illustrate that dynamic behaviors of bolted joint agree with the simulation results and the proposed non-linear contact model was reasonable.

Numerical analysis of the dynamic performance of aerostatic thrust bearings with different restrictors

2018 ◽  
Vol 233 (3) ◽  
pp. 406-423 ◽  
Author(s):  
Hailong Cui ◽  
Yang Wang ◽  
Xiaobin Yue ◽  
Yifei Li ◽  
Zhengyi Jiang
Keyword(s):  
Load Capacity ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Dynamic Mesh ◽  
Eccentricity Ratio ◽  
Thrust Bearings ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping ◽  
The Impact ◽  
The Relationship

This study utilizes a dynamic mesh technology to investigate the dynamic performance of aerostatic thrust bearings with orifice restrictor, multiple restrictors, and porous restrictor. An experiment, which investigates the bearing static load capacity, was carried out to verify the calculation accuracy of dynamic mesh technology. Further, the impact of incentive amplitude, incentive frequency, axial eccentricity ratio, and non-flatness on the bearing dynamic performance was also studied. The results show incentive amplitude effect can be ignored at the condition of amplitude less than 5% film thickness, while the relationship between dynamic characteristics and incentive frequency presented a strong nonlinear relationship in the whole frequency range. The change law of dynamic stiffness and damping coefficient for porous restrictor was quite different from orifice restrictor and multiple restrictors. The bearing dynamic performance increased significantly with the growth of axial eccentricity ratio, and the surface non-flatness enhanced dynamic performance of aerostatic thrust bearings.

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